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AR# 6841

Exemplar Spectrum 1998.2 is connecting GSR on an instantiated OFDT to common Ground causing some trimming.

Description

Keywords: OFDT, instantiate, GND, ground, GSR, ngdbuild, optimize

Urgency: Standard

General Description:

I am using Exemplar Leonardo Spectrum 1998.2e and have instantiatedon OFDT component. After the Optimize command I notice that theGSR signal on the OFDT component is connected to a common groundsignal, even when I am using the STARTUP component. This results in theGSR on the STARTUP also being grounded. The xilinx tools are in turntrimming the OFDT component.

Am I using the OFDT incorrectly? I thought users are not suppose tosignals to the GSR or GTS pins/signals on comps.

Solution

This is correct you are not suppose to connect any signals to the GSRor GTS pins on components, unless it is the STARTUP component,that is bringing the GSR or GTS signal to a device pin. Exemplar Spectrum1998.2 is incorrectly connecting the GSR signal to ground, especially on an instantiated component which synthesis should not touch. This is fixed in the next release of the Exemplar software release 1999.1

The workaround for now is to do a NOOPT on the instances.

Either in the script, or in the GUI at the command line type the following after 'READ' and before 'OPTIMIZE':

set_attribute -inst instance_name -name NOOPT -value TRUE

for example:

set_attribute -inst U1 -name NOOPT -value TRUE

In the GUI you should be able to goto the constraints tab after 'READ'and find the component instance and select the 'NOOPT' check box.